Constant CPU overload errors!!!

[maxxdog]

Sorry if this problem has been raised before - I've done a quick search but couldn't find an answer. I'm running PT 8.0.4 (just installed the update) and I'm getting constant error messages telling me my 'CPU usage is holding off, etc ... (-6104)', even though:

- the disk usage is running at about 15-20% with only a couple of % of Elastic audio (this level of usage has never been a problem)
- checked the compatibility of all plug-ins (no problems there, especially as they've been working fine until now)
- tried every possible combination of Hardware, Playback and Plug-in Buffer sizes (increased H/W Buffer size, used 1 and 2 Host Processors, upped the CPU limit to 90%, engaged and disengaged the 'ignore errors' option, etc, etc)
- have done everything digi suggests for optimizing my system

And yet, when the session craps out, I can't even play back a second of the song!!

What on earth is going on?

[maxxdog]

FYI I'm using:

iMac, 10.5.8, 2.66 GHz IC2D, 4 GB memory.

The tracks are running from a WD ext HDD with very fast processor and samples are running off a second, similar ext HDD.

[maxxdog]

Actually, I should mention, I've just added a bunch of new Bomb Factory plugs - their high end compressors and the Pultec EQ emulations. They don't come up as incompatible on the digi list, but maybe ... ?